The invention relates to a coffee making apparatus, more particularly to an improved grinder and an extractor system for coffee powder.
A conventional coffee mill has a grinder which is rotated horizontally in a case to crush coffee-beans. The grinder is positioned at the bottom of the case and rotated around a driving shaft by a motor, as shown in Japanese Pat No. Sho 58-325 published Jan. 6, 1983, and also in U.S. Pat. No. 4,196,658. The motor is mounted below the case. Therefore, coffee-beans are ground while being rotated horizontally together with the horizontally rotated grinder.
However, such an arrangement is disadvantageous in grinding a small amount of coffee-beans since the beans cannot be sufficiently ground with the grinder blade rotating only in a horizontal plane because an up and down stirring motion cannot be achieved.
In the conventional system, the coffee beans are only uniformly ground if there is exactly the correct amount of beans in the case. If there is more or less than the optimal amount of coffee-beans, all of coffee-beans are not stirred sufficiently, since the grinder only rotates horizontally. Accordingly, part of coffee-beans cannot be sufficiently ground, and the resultant mixture is not uniform in powder size. It is therefore difficult to extract coffee efficiently from the coffee powder.
Moreover, since coffee powder is left in the case after extracting coffee, an oil component of the coffee powder starts to dissolve in the case. If the oil component is left in the case for a long time, the case becomes non-sanitary and polluted because of decomposition of the oil component.
In a conventional apparatus, it is possible for hot water to leak from between the body of the motor and the driving shaft to the interior of the motor. In the conventional type apparatus in which the motor is disposed vertically at the top of the apparatus housing and in which the grinder is disposed on the driving shaft below the motor, it is also possible for steam to enter from between the housing of the motor and the driving shaft to the interior of the motor during coffee extraction. Therefore, it is necessary to completely seal the area between the housing and the driving shaft from hot water and/or steam, a procedure which is quite expensive